Fibronectin EDA and CpG synergize to enhance antigen-specific Th1 and cytotoxic responses

Vaccine. 2016 May 5;34(21):2453-2459. doi: 10.1016/j.vaccine.2016.03.057. Epub 2016 Mar 24.


Subunit vaccines, employing purified protein antigens rather than intact pathogens, require the addition of adjuvants for enhanced immunogenicity with a correct balance between strong activation of the immune system and low toxicity. Here we show that the endogenous (i.e., autologous) non-toxic TLR4 agonist extra domain A type III repeat of fibronectin (FNIII EDA) can synergize with the exogenous (i.e., bacterial), toxic-at-high-dose, TLR9 agonist CpG to induce efficient cellular immune responses while keeping the dose of CpG low. The efficacy of the combined TLR agonists, even at half-doses, led to stronger dendritic cell activation, enhanced cytotoxic T lymphocyte activation as well as stronger humoral response, compared to the individual agonists given at full doses. Immune cells induced after vaccination with the co-adjuvanted formulation could mediate tumor regression in an E.G7-OVA tumor model, and eradicate circulating hepatitis B virus (HBV) in a transgenic HBV model. Together, these results show that endogenous TLR agonists, such as variants of FNIII EDA, can synergize with exogenous TLR ligands, such as CpG, and strongly enhance cellular immune responses, while improving their safety profile.

Keywords: Adaptive immunity; Adjuvant; Cancer vaccine; CpG; FNIII EDA; Hepatitis B virus; Pattern recognition receptors; Toll-like receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / administration & dosage
  • Animals
  • Cancer Vaccines / administration & dosage
  • Cancer Vaccines / immunology*
  • Dendritic Cells / immunology
  • Disease Models, Animal
  • Fibronectins / chemistry
  • Fibronectins / immunology*
  • Hepatitis B / immunology
  • Hepatitis B / virology
  • Hepatitis B Vaccines / administration & dosage
  • Hepatitis B Vaccines / immunology*
  • Hepatitis B virus / immunology
  • Immunity, Cellular
  • Immunity, Humoral
  • Mice
  • Mice, Transgenic
  • Oligodeoxyribonucleotides / immunology*
  • Receptors, Pattern Recognition
  • T-Lymphocytes, Cytotoxic / immunology*
  • Th1 Cells / immunology*
  • Toll-Like Receptor 4 / agonists*
  • Toll-Like Receptor 4 / immunology
  • Toll-Like Receptor 9 / agonists
  • Toll-Like Receptor 9 / immunology
  • Vaccination


  • Adjuvants, Immunologic
  • CPG-oligonucleotide
  • Cancer Vaccines
  • Fibronectins
  • Hepatitis B Vaccines
  • Oligodeoxyribonucleotides
  • Receptors, Pattern Recognition
  • Tlr4 protein, mouse
  • Toll-Like Receptor 4
  • Toll-Like Receptor 9